Okada K, Brown E J
Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110.
J Immunol. 1988 Feb 1;140(3):878-84.
We have examined the effects of NaF on C3b receptor (CR1) expression and function in human polymorphonuclear leukocytes (PMN). Plasma membrane expression of CR1 was determined with a monoclonal antibody (3D9); CR1 function was assessed with erythrocytes bearing C3b (EC3b) or C3b oligomers prepared with avidin and biotin. NaF inhibited in a dose-dependent manner CR1-mediated phagocytosis and NaF inhibited f-met-leu-phe or phorbol dibutyrate-induced increases in CR1 expression, with 50% inhibition at 5 mM NaF. Increased plasma membrane expression of CR3 induced by f-met-leu-phe also was inhibited by NaF. However, increased CR1 and CR3 expression due to incubation at 37 degrees C were unaffected by 10 mM NaF. Incubation of PMN with 10 mM NaF depleted 80% of intracellular adenosine triphosphate (ATP) after 10 min. However, inhibition of CR1 function was unrelated to ATP level, inasmuch as normal increases in CR1 expression and in phagocytosis occurred 20 min after removal of NaF, whereas ATP levels remained below 25% of normal. Strikingly, internalization of soluble oligomeric C3b ligands was unaffected by 10 mM NaF, which completely inhibited phorbol dibutyrate-induced CR1 internalization and EC3b phagocytosis. We conclude that there are two different mechanisms for increasing plasma membrane expression of CR1, one of which is inhibitable by NaF. Moreover, there are two distinct pathways of CR1 internalization which can also be distinguished by their sensitivity to NaF.
我们研究了氟化钠（NaF）对人多形核白细胞（PMN）中C3b受体（CR1）表达及功能的影响。采用单克隆抗体（3D9）测定CR1的质膜表达；通过带有C3b的红细胞（EC3b）或用抗生物素蛋白和生物素制备的C3b寡聚体评估CR1功能。NaF以剂量依赖方式抑制CR1介导的吞噬作用，且NaF抑制甲酰甲硫氨酰-亮氨酰-苯丙氨酸（f-met-leu-phe）或佛波醇二丁酸酯诱导的CR1表达增加，在5 mM NaF时抑制率达50%。f-met-leu-phe诱导的CR3质膜表达增加也被NaF抑制。然而，37℃孵育导致的CR1和CR3表达增加不受10 mM NaF影响。PMN与10 mM NaF孵育10分钟后，细胞内三磷酸腺苷（ATP）耗竭80%。然而，CR1功能的抑制与ATP水平无关，因为去除NaF 20分钟后CR1表达和吞噬作用正常增加，而ATP水平仍低于正常水平的25%。引人注目的是，10 mM NaF不影响可溶性寡聚C3b配体的内化，而其完全抑制佛波醇二丁酸酯诱导的CR1内化和EC3b吞噬作用。我们得出结论，CR1质膜表达增加存在两种不同机制，其中一种可被NaF抑制。此外，CR1内化存在两条不同途径，也可通过它们对NaF的敏感性来区分。
